The present invention relates to an actuation system for a clamping assembly for use in a pipe clamping apparatus. Further, the present invention relates to an internal clamping assembly for a pipe, preferably a backup ring assembly, and to a pipe clamping apparatus comprised of the clamping assembly.
Typically, a pipeline is constructed of a number of pipe lengths or sections which are placed end to end and welded together at the respective adjacent ends as the construction of the pipeline proceeds. In order to achieve a desirable weld between the adjacent ends, the ends of the pipe sections must be clamped or held in close proximity. For this purpose, various pipe clamping apparatuses have been developed for clamping the pipe sections for welding.
Once the clamping apparatus is in place, the welding is typically performed by a welding device outside of or exterior to the pipe sections. During the welding operation, a weld backup ring is preferably provided on the inside or interior surfaces of the pipe sections at the location of the abutment of the adjacent ends of the pipe sections. The backup ring is desirable for supporting the weld pool which would otherwise fall into the pipe sections during the welding operation. Also, the backup ring facilitates the formation of a relatively smooth circumferential weld internally of the pipeline.
Several conventional clamping apparatuses and associated backup rings are described in United Kingdom Patent Application 2,067,945 published Aug. 5, 1981 by Rinaldi, Canadian Patent Application 2,183,156 published Aug. 17, 1995 by Brookhouse, U.S. Pat. No. 5,535,938 issued Jul. 16, 1996 to Leduc, U.S. Pat. No. 3,979,041 issued Sep. 7, 1976 to Kaneyama, U.S. Pat. No. 4,177,914 issued Dec. 11, 1979 to Clavin, U.S. Pat. No. 4,201,326 issued May 6, 1980 to Connell, U.S. Pat. No. 4,285,458 issued Aug. 25, 1981 to Slavens, U.S. Pat. No. 3,741,451 issued Jun. 26, 1973 to Gwin, U.S. Pat. No. 3,937,382 issued Feb. 10, 1976 to Cunningham and U.S. Pat. No. 5,110,031 issued May 5, 1992 to Rinaldi.
Such conventional clamping apparatuses are typically capable of self-propulsion through the pipeline and include independently operable front and rear clamping mechanisms for clamping the adjacent pipe sections for welding and a backup ring for providing backup support at the weld. More particularly, the front pipe clamping mechanism comprises a plurality of clamping shoes radially movable between a retracted position and an extended position for engaging the interior surface of the front pipe section. The rear pipe clamping mechanism is also comprised of a plurality of clamping shoes radially movable between a retracted position and an extended position for engaging the interior surface of the rear pipe section.
The backup ring is similarly comprised of a plurality of segments movable between a retracted position and an extended position for engaging the interior surface of the front and rear pipes at their adjacent ends. Typically, the backup ring, is mounted with the front and rear pipe clamping mechanisms. For instance, the backup ring may either form part of, or be extendible and retractable simultaneously with, one or both of the front and rear clamping mechanisms of the associated pipe clamping apparatus. However, the backup ring may be also be retractable and extendible independently of the clamping mechanisms.
Each of the above apparatuses tends to have a relatively complicated or complex structure and tends to be relatively large-scaled. As a result, each apparatus tends to be primarily useful in larger diameter pipes. In other words, the structure and size of each of these apparatuses may result in difficulties when attempting to reduce the size of the apparatus for smaller diameter pipes. Accordingly, various attempts have been made to provide a pipe clamping apparatus which may be reduced in size to be particularly useful for medium to smaller diameter pipes, such as those having a diameter of between about 16 inches (40.64 cm) and 32 inches (81.28 cm). However, none of these attempts have been fully satisfactory.
Canadian Patent No. 1,060,488 issued Aug. 14, 1979 to Lajoie et. al. is directed at a pipe clamping apparatus comprised of a longitudinally disposed piston rod having a pneumatic piston fixed at one end thereof which is movable within a stationary cylinder. A plurality of radial elements for engaging the interior surface of the pipe are coupled with the other end of the longitudinal piston rod by a plurality of links or toggles. Specifically, the plurality of links or toggles attach or connect each of the radial elements to the longitudinal piston rod. When the piston is energized, the piston and the piston rod affixed thereto move as a unit longitudinally in a direction towards the links to apply a longitudinal force. The longitudinal force creates a compressive force in the links or toggles connected between the piston rod and the radial elements to move the radial elements radially outwards to engage the pipe surface. When the piston is no longer energized, the piston is biased by a compression spring to return to its initial position to move the radial elements radially inwards to disengage the pipe surface.
Canadian Patent No. 1,269,825 issued Jun. 5, 1990 to Okamoto describes a device for internally clamping pipes comprised of a longitudinally disposed guide bar and a pair of axially spaced apart pressure chambers or cylinders. A piston is fitted movably around the guide bar within each pressure chamber such that the piston is movable along the stationary guide bar within the chamber. A plurality of retractable clamps for engaging the inner surface of the pipe are connected with, and actuated by, each of the pistons by a plurality of actuating links. In other words, the plurality of actuating links attach or connect each of the clamps to one of the pistons. To actuate the device, pressurized fluid is supplied to each pressure chamber which acts upon each piston to move the piston longitudinally along the guide bar within the pressure chamber. Longitudinal movement of the piston along the guide bar causes the actuating links connected with each piston to move the clamps radially outwards for engagement with the pipe surface. Return springs are provided for acting upon each piston to return the piston to its initial position to retract the clamps upon release of the fluid pressure.
U.S. Pat. No. 3,937,382 issued Feb. 10, 1976 to Cunningham also describes a clamping apparatus which includes a first and a second set of clamping members and a weld backup mounted about a central shaft. The mechanism for actuation of the clamping members differs from the mechanism for actuation of the weld backup. Each set of clamp members is actuated by a longitudinally disposed piston rod slidably received upon the central shaft and rigidly coupled with a piston at one end thereof, which piston is movably received within a stationary cylinder. A hub is rigidly affixed to the piston rod. Further, the clamp members are coupled with the hub by a plurality of links or toggles. Specifically, the plurality of links or toggles attach or connect each of the clamp members to the hub which is rigidly affixed to the longitudinal piston rod. When the piston is energized in a first direction, the piston, the piston rod and the hub affixed thereto move as a unit longitudinally in a direction towards the links. Longitudinal movement of the hub along the central shaft causes the links connected between the hub and the clamping members to move the clamping members radially outwards for engagement with the pipe surface. Energization of the piston in an opposed direction moves the piston, the piston rod and the hub as a unit longitudinally in an opposite direction away from the links to move the clamping members radially inwards to disengage the pipe surface.
The weld backup is comprised of a central hub which is rigidly mounted about the central shaft and a ring housing which is rigidly mounted with the central hub. The ring housing defines a plurality of circumferentially spaced cylinders, each having a piston mounted therein for radial movement within the cylinder. Each of the pistons has an end associated with a copper backup shoe. Two-way radial movement of each of the pistons is affected by a flow of fluid into the cylinder accommodating the piston, which results in the extension and retraction of the associated backup shoes.
U.S. Pat. No. 3,979,041 issued Sep. 7, 1976 to Kaneyama, U.S. Pat. No. 5,356,067 issued Oct. 18, 1994 to Leduc and U.S. Pat. No. 5,597,108 issued Jan. 28, 1997 to Dierlam also describe a pipe clamping apparatus comprised of a longitudinally disposed piston rod having a double acting piston fixed at one end thereof, which piston is movable within a stationary cylinder. A hub, ring or body is rigidly affixed with the other end of the movable piston rod. Further, a plurality of backup shoes for engaging the interior surface of the pipe are coupled with the hub, ring or body by a plurality of links or crank arms. Specifically, the plurality of links or crank arms attach or connect each of the backup shoes to the hub, ring or body, which is in turn rigidly affixed with the longitudinally movable piston rod. When the piston is energized in a first direction within the stationary cylinder, the piston, the piston rod and the hub, ring or body move as a unit longitudinally in a direction towards the links or crank arms, which cause the backup shoes to move radially outwards. Energization of the piston within the stationary cylinder in an opposed direction moves the piston, the piston rod and the hub, ring or body as a unit longitudinally in a direction away from the links or crank arms, which cause the backup shoes to move radially inwards.
There remains a need in the industry for an improved internal clamping assembly for a pipe and particularly, for an improved backup ring assembly. The improved internal clamping apparatus and improved backup ring assembly are preferably suitable for use with a pipe having any diameter. However, there further remains a need in the industry for an internal pipe clamping assembly, including a backup ring assembly, which is suitable for use for medium to smaller diameter pipes such as those having a diameter of between about 16 inches (40.64 cm) and 32 inches (81.28 cm). Finally, there is a need for a backup ring assembly having a relatively simple structure and which is relatively easily retrofittable to an existing pipe clamping apparatus.
The present invention relates to an actuation system for a pipe clamping assembly for use in an internal pipe clamping apparatus. Further, the present invention relates to an internal clamping assembly for a pipe and to a pipe clamping apparatus comprised of the clamping assembly. Preferably, the clamping assembly is comprised of a backup ring assembly. However, the clamping assembly may also be comprised of a front clamping mechanism or a rear clamping mechanism for a pipe clamping apparatus.
The actuation system for the clamping assembly preferably has a relatively simple structure and is relatively easily retrofittable to an existing pipe clamping apparatus. The pipe clamping apparatus, including the actuation system and the clamping assembly, is suitable for use with a pipe having any diameter. However, the pipe clamping apparatus, including the actuation system and the clamping assembly, is particularly suitable for use for medium to smaller diameter pipes such as those having a diameter of between about 16 inches (40.64 cm) and 32 inches (81.28 cm). In addition, the pipe clamping apparatus preferably permits the operation of the backup ring assembly independently of the front and rear clamping mechanisms.
More particularly, the present invention relates to an actuation system for a clamping assembly for engaging an interior surface of a pipe for use in a pipe clamping apparatus. The actuation system comprises:
(a) a shaft having a longitudinal axis;
(b) an actuator defining an actuator chamber therein having a peripheral chamber wall and wherein the actuator is movably mounted about the shaft such that the shaft extends through the actuator chamber and such that the actuator is longitudinally reciprocable thereon; and
(c) a piston fixedly mounted about the shaft and positioned within the actuator chamber, wherein the piston has a first side, a second side and an outer perimeter sealingly engaging the peripheral chamber wall to create a first chamber adjacent the first side of the piston and a second chamber adjacent the second side of the piston such that the actuator reciprocates along the shaft in response to a differential force applied within the first chamber and the second chamber;
wherein the clamping assembly is associated with the actuator such that reciprocation of the actuator along the shaft causes the clamping assembly to move radially relative to the longitudinal axis of the shaft.
The clamping assembly may comprise a front clamping mechanism, a rear clamping mechanism or a backup ring assembly of a pipe clamping apparatus or any other similar assembly in which radial movement of internal clamping units is necessary. In the preferred embodiment, the clamping assembly is comprised of a backup ring assembly.
Further, the actuation system is preferably adapted to be mounted between a front clamping mechanism and a rear clamping mechanism in the pipe clamping apparatus as part of an internal backup ring system. More particularly, in the preferred embodiment, the shaft of the actuation system is adapted to be fixedly mounted between the front clamping mechanism and the rear clamping mechanism in the pipe clamping apparatus.
At least one of the first chamber and the second chamber is preferably adapted to contain a pressurized fluid for providing the differential force. In other words, the pressurized fluid applies a force in at least one of the first and second chambers, wherein the differential between the force applied in the first chamber and the force applied in the second chamber causes the actuator to reciprocate along the shaft. Where only one of the first or second chambers is adapted to contain a pressurized fluid, an opposing force in the other of the first and second chambers may be provided or applied by any mechanism capable of or suitable for urging the reciprocation of the actuator in the desired direction, such as a return or compression spring.
However, in the preferred embodiment, the first chamber is adapted to contain a first pressurized fluid and the second chamber is adapted to contain a second pressurized fluid, wherein the first pressurized fluid and the second pressurized fluid provide the differential force for reciprocating the actuator along the shaft. In other words, the actuator is caused to longitudinally reciprocate along the shaft in both directions as a result of the differential force provided by the first and second pressurized fluids.
Thus, the actuation system is further preferably comprised of a fluid feed mechanism associated with at least one of the first chamber and the second chamber for communicating the pressurized fluid to provide the differential force. In the preferred embodiment, the actuation system is comprised of a fluid feed mechanism associated with each of the first chamber and the second chamber for communicating the first pressurized fluid and the second pressurized fluid to provide the differential fluid. Either a hydraulic or pneumatic fluid feed mechanism may be used. In other words, the pressurized fluid may be any suitable liquid or gas. However, preferably the actuation system is pneumatically actuated or powered.
Any type or configuration of fluid feed mechanism capable of feeding, supplying, providing or otherwise communicating the desired first and second pressurized fluids to the first and second chambers respectively may be used. However, preferably, the fluid feed mechanism selectively communicates the first pressurized fluid to the first chamber and the second pressurized fluid to the second chamber to provide the differential force to selectively cause the actuator to reciprocate along the shaft in first and second directions.
In the preferred embodiment, the fluid feed mechanism is comprised of a first fluid port associated with the first chamber for communicating the first pressurized fluid to cause the actuator to reciprocate along the shaft in a first direction and a second fluid port associated with the second chamber for communicating the second pressurized fluid to cause the actuator to reciprocate along the shaft in a second direction. The first fluid port is comprised of one or more apertures, as required or desired, to permit the effective communication of the first pressurized fluid with the first chamber. Similarly, the second fluid port is comprised of one or more apertures, as required or desired, to permit the effective communication of the second pressurized fluid with the second chamber.
The fluid feed mechanism is further preferably comprised of a first fluid conduit for conducting the first pressurized fluid to the first fluid port and a second fluid conduit for conducting the second pressurized fluid to the second fluid port. The first and second fluid conduits may extend through the actuation system in any manner and along any path permitting the functioning of the actuation system, while providing the necessary pressurized fluid. However, preferably, at least a portion of each of the first and second fluid conduits extends through the shaft.
The clamping assembly may be associated with the actuator by any mechanism, apparatus or structure which permits the reciprocation of the actuator along the shaft to cause the clamping assembly to move radially relative to the longitudinal axis of the shaft for engaging the interior surface of the pipe. For instance, the clamping assembly may be directly mounted or affixed with the actuator. Alternately, the clamping assembly may be indirectly affixed or mounted with the actuator by one or more links or toggles such that reciprocation of the actuator causes the links or toggles to act upon the clamping assembly to move the clamping assembly radially to engage the interior surface of the pipe.
However, preferably the actuator is comprised of at least one camming surface and the clamping assembly is associated with the camming surface such that reciprocation of the actuator along the shaft moves the clamping assembly along the camming surface to cause the clamping assembly to move radially relative to the longitudinal axis of the shaft. More particularly, in the preferred embodiment, the backup ring assembly is associated with the camming surface such that reciprocation of the actuator along the shaft moves the backup ring assembly along the camming surface to cause the backup ring assembly to move radially relative to the longitudinal axis of the shaft.
The camming surface may be located on, about or within the actuator in any position and may have any structure or configuration permitting the camming surface to cause the radial movement of the backup ring assembly. Further, the camming surface may have any position or location on, about or within the actuator relative to the actuator chamber. The particular location or position of the camming surface may be determined, at least in part, by the size or diameter of the pipe in which the pipe clamping apparatus is to be inserted. For instance, the camming surface may be longitudinally spaced apart from the actuator chamber. In the preferred embodiment, the camming surface is radially spaced apart from the actuator chamber. Further, the actuator has an outer perimeter and the camming surfaces are preferably circumferentially spaced about the outer perimeter of the actuator.
Further, in the preferred embodiment, each camming surface preferably comprises a camming slot. Each camming slot preferably has an outermost end and the outermost end of each camming slot preferably extends to the outer perimeter of the actuator so that the backup shoe units are removable from the backup ring assembly when the backup shoe units are in the extended position and the pipe clamping apparatus is not positioned inside a pipe. A releasable retainer may also be associated with each backup shoe unit to releasably retain the backup shoe units relative to the camming slot when the backup shoe units are in the extended position and the pipe clamping apparatus is not positioned inside the pipe.
The actuator may be comprised of any type or configuration of housing, casing or enclosure which defines a chamber therein and which may be movably mounted about the shaft as discussed herein. Preferably, the actuator has a generally cylindrical outer perimeter. Further, in the preferred embodiment, the actuator is comprised of a cylinder defining the actuator chamber for containing the piston therein. Thus, the camming surfaces are associated with the cylinder, which is movable upon the piston fixedly mounted about the shaft. Further, the actuator chamber defined by the actuator may have any shape or configuration compatible with the piston positioned therein. Conversely, the piston may have any shape or configuration compatible with the actuator chamber in which it is received. However, in the preferred embodiment, the actuator chamber is cylindrical for receiving a disc-shaped piston.
Any backup ring assembly capable of accommodating the radial movements described herein may be used in the invention. In the preferred embodiment, the backup ring assembly is comprised of a plurality of backup shoe units. In this instance, the plurality of backup shoe units engage the camming surfaces so that reciprocation of the actuator along the shaft causes the backup shoe units to move radially relative to the longitudinal axis of the shaft by moving along the camming surfaces. Further, in the preferred embodiment, reciprocation of the actuator along the shaft in a first direction causes the backup shoe units to move radially outward toward an extended position for engaging the interior surface of the pipe and reciprocation of the actuator along the shaft in a second direction causes the backup shoe units to move radially inward toward a retracted position.
The backup shoe units are preferably capable of a limited range of radial movement between an inner limit and an outer limit without reciprocation of the actuator along the shaft. Further, each of the backup shoe units preferably comprises an urging mechanism for urging the backup shoe units toward the outer limit of the limited range of radial movement. Any biasing device or mechanism capable of urging the backup shoe units in the desired manner, such as a spring, may be used.
Preferably, the outer limit of the limited range of radial movement is substantially similar for each backup shoe unit. However, the outer limit of the limited range of radial movement of the backup shoe units may vary so that reciprocation of the actuator along the shaft in the second direction causes the backup shoe units to move radially inward sequentially toward the retracted position as the backup shoe units sequentially reach the outer limit of the limited range of radial movement.
The outer limit of the limited range of radial movement may be varied in any manner compatible with the operation of the backup shoe units. However, preferably, the outer limit of the limited range of radial movement of the backup shoe units is varied, where it is desired to do so, by inserting one or more shims in the backup shoe units to alter the outer limit. The backup ring system may also be adapted for use with different sizes of pipes by using one or more shims to selectively increase or decrease the outer limit of the limited range of radial movement.
The shaft of the actuation system is preferably adapted to be fixedly mounted in the pipe clamping apparatus. As stated, where the clamping apparatus is a backup ring assembly, the shaft is adapted to be fixedly mounted between the front and rear clamping mechanisms. More particularly, the shaft is preferably fixedly mounted in a manner such that the longitudinal movement of the shaft within the actuation system, that is, movement along its longitudinal axis, is inhibited. As a result, the actuator is movable along the fixed shaft. Further, the shaft is preferably fixedly mounted in a manner such that rotation of the shaft within the actuator is inhibited.
Preferably, the actuation system is further comprised of an alignment plate disposed in a plane which is substantially perpendicular to the longitudinal axis of the shaft, wherein the alignment plate is fixedly mounted about the shaft such that the shaft extends therethrough. The alignment plate is preferably adapted to be fixedly mounted or connected with the pipe clamping apparatus so that the alignment plate is inhibited from longitudinally or rotationally moving relative to, or within, the pipe clamping apparatus. Further, the alignment plate preferably comprises a guide ring extending about a perimeter of the alignment plate in a plane substantially perpendicular to the plane of the alignment plate in a direction toward the actuator so that that the alignment plate defines an actuator housing and wherein the actuator is contained within the actuator housing.
The backup shoe units are preferably received in and extend through the guide ring. The backup shoe units may be received in the guide ring in any manner compatible with the operation of the backup ring assembly. However, preferably the guide ring defines a plurality of sleeves for receiving the plurality of backup shoe units. The guide ring may have any structure or configuration capable of providing the actuator housing.
The actuation system may also be comprised of an auxiliary mechanism for dislodging the backup ring assembly when at least one of the backup shoe units is stuck to the interior surface of the pipe in the extended position and cannot be dislodged by the primary mechanism. The auxiliary dislodging mechanism may be associated either with one or more of the backup shoe units or with the actuator, and may include one or more of the following auxiliary dislodging mechanisms or some other mechanism, member or structure which performs a dislodging function.
Where at least one of the front clamping mechanism and the rear clamping mechanism is capable of radial movement inward and outward relative to the longitudinal axis of the shaft, the auxiliary dislodging mechanism may be comprised of an engagement surface on at least one of the backup shoe units for engaging at least one of the front clamping mechanism and the rear clamping mechanism in response to inward radial movement of the clamping mechanism when the backup shoe unit is not in the retracted position in order to urge the backup shoe unit radially inward.
The auxiliary dislodging mechanism may also be comprised of a variance of the outer limit of the limited range of radial movement of the backup shoe units. As stated above, the outer limit of the limited range of radial movement of the backup shoe units may vary so that reciprocation of the actuator along the shaft in the second direction causes the backup shoe units to move radially inward sequentially toward the retracted position as the backup shoe units sequentially reach the outer limit of the limited range of radial movement. This sequential radially inward movement may act to dislodge the backup ring assembly.
The auxiliary dislodging mechanism may also be comprised of a variance in the configuration of two or more of the camming surfaces on the actuator so that reciprocation of the actuator along the shaft in the second direction causes the backup shoe units to move radially inward sequentially toward the retracted position as the backup shoe units sequentially reach the outer limit of the limited range of radial movement. The configuration of the camming surfaces is preferably varied by varying one or more of their shape or slope or their distance from the longitudinal axis of the shaft.
Whether the outer limit of the limited range of radial movement of the backup shoe units is varied or the configuration of each of the camming surfaces is varied, the backup shoe units may move radially inward sequentially in any manner. In particular, the backup shoe units may move radially inwardly sequentially either individually or in one or more groupings of backup shoe units. Further, each individual backup shoe unit or each grouping of backup shoe units may move E) radially inwardly in any order or succession as compared with any other individual backup shoe unit or any other grouping of backup shoe units.
The clamping assembly may be actuated by the actuation system in any order or in any sequence as compared with the other components of the pipe clamping mechanism. For instance, in the preferred embodiment, the backup ring assembly may be actuated concurrently with one or both of the front and rear clamping mechanisms of the pipe clamping apparatus. However, preferably, the backup ring assembly is actuated independently of both the front clamping mechanism and the rear clamping mechanism.
Finally, the front clamping mechanism of the pipe clamping apparatus is preferably of a type capable of radial movement relative to the longitudinal axis of the shaft between an extended position and a retracted position. Similarly, the rear clamping mechanism is preferably of a type capable of radial movement relative to the longitudinal axis of the shaft between an extended position and a retracted position.
In the retracted positions, the front clamping mechanism, the rear clamping mechanism and the backup ring assembly may each extend any distance from the longitudinal axis of the shaft. However, in the preferred embodiment, in the retracted positions at least the front clamping mechanism, and most preferably the rear clamping mechanism as well, extend further from the longitudinal axis of the shaft than does the backup ring assembly. This configuration may serve to protect the backup ring assembly from damage when moving through the pipe.
Conversely, the backup ring assembly is capable of extending at least as far and preferably further from the longitudinal axis of the shaft than are the front clamping mechanism or the rear clamping mechanism when each of the front clamping mechanism, the rear clamping mechanism and the backup ring assembly are in the extended position, thus enabling the backup ring assembly to engage the interior surface of the pipe under such conditions.
As a result, the radial distance of travel of the backup ring assembly between the extended and retracted positions is preferably greater than the radial distance of travel of the front and rear clamping mechanisms between these positions. Since the radial distance of travel of the backup ring assembly is a function of the amount of longitudinal reciprocation or longitudinal travel of the actuator between the extended and retracted positions and the slope of the camming surfaces, the radial distance of travel of the backup ring assembly may be varied by varying these parameters in order to achieve the desired radial distance of travel.